Q&A What you should know about Milestone® specialty

Vegetation managers and foresters rely on Milestone® specialty Will Milestone® specialty herbicide work herbicide to control unwanted weeds and brush beneath electrical in a tank mix? power lines; along railroad beds, roadsides and pipelines; in commercial forestry 1 and wildlife openings, including grazed areas Milestone is an excellent tank-mix partner and is compatible on these sites; and on range and pasture and Conservation Reserve with most other . Tank-mixing Milestone improves Program (CRP) sites. Milestone is a flexible formulation that can be control of conifers, brush and hardwood species, and when mixed ® used in a variety of ways to achieve vegetation management goals. with Garlon 3A specialty herbicide, it provides an excellent solution for chemical side trimming. A nonionic surfactant may be added to The following information provides specifics on Milestone and improve spreading on leaves and uptake through the leaf cuticles. explores questions often asked concerning its use. When tank-mixing, use only in accordance with the most restrictive precautions and limitations on the respective product labels, and What is Milestone? always perform a jar test to ensure the compatibility of the Milestone from Dow AgroSciences is designed and developed products being used. specifically for long-lasting control of problem weeds and certain woody brush, vines and legumes, including noxious and invasive Does Milestone stay where you spray it? species. Milestone® specialty herbicide is registered for use on Because of its formulation, aminopyralid is essentially nonvolatile. noncropland areas, including industrial sites and rights-of-way It settles on the application site and won’t change into a gas that (such as roadsides, electric utility and communication transmission can be carried off the application site by air movement. Milestone lines, pipelines and railroads). It also is accepted for use in forested can be applied aerially or by ground through broadcast or spot areas,1 nonirrigation ditch banks, natural areas (such as wildlife treatment applications, or added to basal bark mixtures for enhanced management areas, wildlife openings, wildlife habitats, recreation control of target species. Users still must follow all label precautions areas, campgrounds, trailheads and trails), and grazed areas in and so spray drift does not occur. around these sites. What is the active ingredient in Milestone? Which weeds does Milestone® specialty The active ingredient in Milestone is aminopyralid, developed and herbicide control? patented by Dow AgroSciences specifically for the management of Milestone is labeled for consistent and dependable control of susceptible broadleaf weeds, including many noxious and invasive susceptible noxious and invasive broadleaf plants and woody brush, plant species. It is effective at low rates (3 to 7 fluid ounces including horseweed (marestail), Canada thistle, musk thistle and of product per acre) as compared with most other registered other biennial thistles, knapweeds, annual fleabane, kudzu, perennial herbicides, including 2,4-D, , , and sowthistle, prickly lettuce, henbit, common ragweed and yellow . In addition to low use rates, it provides residual control, starthistle. Field trials have shown that it provides effective control which reduces the need for re-treatment in areas with the potential with little or no injury to desirable cool- and warm-season grasses, for susceptible weed seeds to germinate. including bermudagrass and bahiagrass. See the product label for a complete list of weeds Milestone controls. How does Milestone work? Milestone works systemically, translocating throughout the entire What are the use rates for Milestone? plant and accumulating in meristematic tissues, including the roots. Milestone controls labeled weeds at rates of 3 to 7 fluid ounces It interferes with plant growth metabolic pathways affecting the per acre, which puts fewer pounds of active ingredient in the growth process. The disruption of plant growth results in the control environment than industry standards. It controls many key broadleaf and death of susceptible plant species. weed species at rates substantially lower than other currently registered herbicides. On all labeled use sites, it is important not Because of its essentially nonvolatile formulation and low use to apply more than 7 fluid ounces per acre of Milestone® specialty rates, Milestone provides effective control with reduced exposure to herbicide per growing season as a result of broadcast, including workers and the environment. In addition, it can be sprayed up to the repeat applications, or more than 14 fluid ounces as a spot water’s edge. application. What is the effect of Milestone on animals Will plants become resistant to Milestone? and humans? Aminopyralid has an auxinic growth regulator mode of action. Despite In Dow AgroSciences laboratory testing, aminopyralid has been extensive use, herbicides with this mode of action have demonstrated shown to be “practically nontoxic” to birds, fish, honeybees, a low risk of resistance compared with herbicides that have other earthworms and aquatic invertebrates. “Practically nontoxic” is the mode-of-action classifications, such as ALS inhibitors, photosystem II EPA’s least toxic category. While aminopyralid is slightly toxic to the inhibitors or ACCase inhibitors. eastern oyster, algae and aquatic vascular plants, it would require rates of application far beyond what is recommended by the product What happens to plants after they’ve label for weed control to raise the risk above any level of concern been treated? established for these organisms by the EPA. Within hours or days of application, the stems and leaves of labeled All pesticides sold in the United States must be accepted for weeds stop growing and turn brown, with few exceptions. Most registration by the EPA based on a minimum of 120 scientific annual susceptible weeds will be controlled within four to eight studies showing that the pesticide will perform its intended function weeks after application; however, complete control of main stems without “unreasonable adverse effects” on humans, animals or the and roots may take longer. Milestone is primarily a postemergence environment. The EPA defines “unreasonable adverse effects” as any herbicide, but also has preemergence soil residual activity on many unreasonable risk to man or the environment, taking into account important weeds. It can be applied to weeds at any growth stage, the economic, social and environmental costs and benefits of the but specific weeds may have optimal growth stages for control. use of the pesticide. (See Table 1 on Page 3.) Because of its residual activity, control may last all season long or, Researchers determine the highest dose of a product that still shows depending on the weed species, into the season after application. no negative effect on animals and call this the No-Observable- The residual activity also helps control germinating seeds of Adverse-Effect Level (NOAEL). Scientists also determine a maximum susceptible weeds. Long-term control is extended if desirable plants exposure level — exposure to the highest estimated concentration move into the treated area, effectively outcompeting the reinfestation level that could be expected with normal use. Using these two of the target weeds. measurements, they calculate a “safety factor.” This factor shows a What is the environmental impact of Milestone? multiple of the highest labeled application rate that an animal would have to be exposed to in order to reach NOAEL. Milestone has been reviewed and registered under the Reduced Risk Pesticide Initiative of the U.S. Environmental Protection Agency (EPA). Aminopyralid’s acute toxicity has been found to be Category IV for This program is reserved for compounds that demonstrate less risk acute oral and dermal toxicity (least toxic rating) by the EPA. Acute to humans and the environment than market standards. Milestone® toxicity is commonly measured by the single-exposure lethal dose specialty herbicide carries a “Caution” signal word and does not or lethal concentration that causes death in 50 percent of treated require a special license for purchase or application. laboratory animals. LD50 indicates the lethal dose of a chemical per unit body weight of an animal and is expressed as milligrams Table 1. Environmental toxicology tests with aminopyralid.

Study Species Value Birds Avian oral Bobwhite quail LD > 2,250 mg ae/kg bw 50 Avian dietary Bobwhite quail LD > 5,620 mg ae/kg diet 50 Avian dietary Mallard duck LD > 5,620 mg ae/kg diet 50 Fish Acute toxicity Rainbow trout 96 hr LC > 100 mg ae/L 50 Acute toxicity Bluegill 96 hr LC > 100 mg ae/L 50 Acute toxicity Sheepshead minnow 96 hr LC > 120 mg ae/L 50 Aquatic Invertebrates Acute toxicity Water flea ( ) 48 hr EC > 100 mg ae/L Daphnia magna 50 Acute toxicity Mysid shrimp 96 hr LC > 100 mg ae/L 50 Acute toxicity Eastern oyster Slightly toxic 48 hr EC > 89 mg ae/L 50 Growth and reproduction Water flea Daphnia( magna) NOEC = 100 mg ae/L Chronic toxicity Midge NOEC = 130 mg ae/L Honeybees Acute contact Honeybee 48 hr LD > 100 ug ae/bee 50 Acute oral Honeybee 48 hr LD > 120 ug ae/bee 50 Earthworm Acute toxicity Earthworm 14 d LC > 1,000 mg ae/kg soil 50 Algae and Aquatic Plants Acute toxicity Freshwater green algae Slightly toxic 72 hr E C = 30 mg ae/L r 50 Acute toxicity Freshwater blue-green algae Slightly toxic 120 hr EC = 27 mg ae/L 50 Acute toxicity Saltwater diatom Slightly toxic 72 hr E C = 77 mg ae/L b 50 Acute toxicity Freshwater diatom Slightly toxic 96 hr EC = 14 mg ae/L 50 Acute toxicity Duckweed ( ) Slightly toxic 14 d EC > 88 mg ae/L Lemna gibba 50

per kilogram (mg/kg). LC50 is the lethal concentration of a chemical Additionally, tests on aminopyralid have concluded it is “not per volume of air or water and is expressed as milligrams per liter likely to be carcinogenic to humans” as classified by the EPA, is

(mg/L). More toxic compounds carry a low value of LD50 or LC50, nonmutagenic, does not interfere with reproduction and has no while practically nontoxic compounds have a high value. adverse neurological effects. (See Table 2 on Page 4.) How does this relate to my protection? Table 2. Mammalian chronic toxicity studies with aminopyralid. If you were to become exposed, it might happen during mixing or Test Species Toxicity Parameters handling the product at application, or through skin absorption from 2-year chronic Rat Not carcinogenic touching treated vegetation before it dries, or through accidental feeding NOAEL (mg/kg/day): ingestion, like eating treated berries. To avoid exposure from the Male = 50, Female = 500 application, when using a handgun, you can apply the spray to the Teratogenicity Rat Not teratogenic foliage and back out of the treated area to avoid walking through NOAEL (mg/kg/day): wet, treated vegetation and you can stay away from the treated area Maternal = 1,000 Developmental = 1,000 until leaves, stems and bark have dried. Since the product is rapidly absorbed into the vegetation, you can limit your exposure by using Teratogenicity Rabbit Not teratogenic common sense and avoiding the area until the vegetation has dried. NOAEL (mg/kg/day): Maternal = 250 What if I walk across a treated area? Developmental = 500 Reproductive Rat No adverse Exposure may occur from walking into an area that is still wet from a toxicity reproductive effects foliar treatment. However, the dose received from this type of activity NOAEL (mg/kg/day): should not be high enough to cause harm. Applicators should always Parental = 1,000 wash their clothing, separately from other laundry, every day after Reproductive = 1,000 work. Scientists have determined “there is no route of exposure or Acute and chronic Rat No adverse scenario suggesting that the general public will be at any substantial neurotoxicity neurological effects risk from longer-term exposure to aminopyralid even when the NOAEL (mg/kg/day) = 1,000 compound is applied at the maximum labeled application rate.”2 Mutagenicity Ames test Negative Assay (in vitro) Do I need to stay indoors during Mutagenicity CHO/HGPRT Negative the application? Assay (in vitro) Mutagenicity Mouse Negative No. However, it’s a good idea to stay away from the application site Assay (in vitro) micronucleus during treatment and until the vegetation dries. After applicators apply the foliar treatment, avoid the area until the vegetation dries. Whom may I contact for more information? Contact your Dow AgroSciences vegetation management specialist or call the Customer Information Center at 800-263-1196 for more information about Milestone or aminopyralid, or visit www.Milestonevmherbicide.com.

1Milestone specialty herbicide is labeled for use in forestry site preparation treatments in AL, AR, GA, LA, MN, MS, NC, SC, TX and VA. 2Aminopyralid Human Health and Ecological Risk Assessment. U.S. Forest Service and National Park Service. June 2007. ®Trademark of Dow AgroSciences LLC When treating areas in and around roadside or utility rights-of-way that are or will be grazed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details. Always read and follow label directions. ©2011 Dow AgroSciences LLC

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